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variable(n)                           Tcl Built-In Commands                           variable(n)



_________________________________________________________________________________________________

NAME
       variable - create and initialize a namespace variable

SYNOPSIS
       variable ?name value...? name ?value?
_________________________________________________________________


DESCRIPTION
       This  command is normally used within a namespace eval command to create one or more vari-
       ables within a namespace.  Each variable name is initialized with value.   The  value  for
       the last variable is optional.

       If a variable name does not exist, it is created.  In this case, if value is specified, it
       is assigned to the newly created variable.  If no value is specified, the new variable  is
       left  undefined.  If the variable already exists, it is set to value if value is specified
       or left unchanged if no value is given.  Normally, name is unqualified (does  not  include
       the names of any containing namespaces), and the variable is created in the current names-
       pace.  If name includes any namespace qualifiers, the variable is created in the specified
       namespace.  If the variable is not defined, it will be visible to the namespace which com-
       mand, but not to the info exists command.

       If the variable command is executed inside a Tcl procedure,  it  creates  local  variables
       linked  to the corresponding namespace variables (and therefore these variables are listed
       by info vars.)  In this way the variable command resembles the  global  command,  although
       the  global  command  only  links to variables in the global namespace.  If any values are
       given, they are used to modify the values of the associated  namespace  variables.   If  a
       namespace variable does not exist, it is created and optionally initialized.

       A  name argument cannot reference an element within an array.  Instead, name should refer-
       ence the entire array, and the initialization value should be left off.  After  the  vari-
       able  has  been declared, elements within the array can be set using ordinary set or array
       commands.

EXAMPLES
       Create a variable in a namespace:
              namespace eval foo {
                  variable bar 12345
              }

       Create an array in a namespace:
              namespace eval someNS {
                  variable someAry
                  array set someAry {
                      someName  someValue
                      otherName otherValue
                  }
              }

       Access variables in namespaces from a procedure:
              namespace eval foo {
                  proc spong {} {
                      # Variable in this namespace
                      variable bar
                      puts "bar is $bar"

                      # Variable in another namespace
                      variable ::someNS::someAry
                      parray someAry
                  }
              }


SEE ALSO
       global(n), namespace(n), upvar(n)


KEYWORDS
       global, namespace, procedure, variable



Tcl                                            8.0                                    variable(n)

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